The present invention relates to a plasma arc torch of the type commonly used to cut or weld a metal workpiece.
U.S. Pat. No. 5,393,952 discloses a plasma arc torch having a water cooled electrode, and a nozzle positioned to form a plasma gas passage between the electrode and the nozzle and leading to a nozzle discharge opening immediately below the electrode. The nozzle is mounted on a gas swirl baffle which is interposed between the electrode and the nozzle. Also, a nozzle cap covers the nozzle, and an outer shield surrounds the nozzle cap so as to define a shielding gas passage which exits about the discharge opening of the nozzle.
It is an object of the present invention to provide an improved plasma arc torch of the described type, and wherein the nozzle is supported directly by the torch body so as to be accurately located, both concentrically and longitudinally with respect to the other torch components.
It is also an object of the present invention to provide an improved plasma arc torch which avoids the use of a cutting gas swirl baffle or ring for mounting the nozzle, and whereby the nozzle may be more accurately seated and located with respect to the other torch components.
It is a further object of the present invention to provide a plasma arc torch having a heat shield assembly surrounding the nozzle so as to define a shielding gas passage therebetween, and wherein the heat shield assembly also retains the nozzle, and defines a portion of a water cooling passage which cools the outside of the nozzle.